The invention is directed to the fastening field, particularly to the mounting of devices within a component. An electrical work box is a receptacle, generally of metallic or of thermoplastic composition, designed to support an electrical device. The electrical device may be a switch or plug receptacle in single, dual or multiple “gang” configurations, a lighting fixture, a ceiling fan, a speaker, or an alarm. The electrical work box may also provide wiring junctions for electrical applications, such as low voltage applications associated with audio/visual devices, telephone devices and computer networking devices.
In new construction, electrical work boxes are generally mounted to exposed studs or framing elements using nails or screws. In existing construction, electrical work boxes may be affixed to existing walls, including wallboard, lathe and plaster or other wall surfaces that have been mounted over framing. Such boxes are commonly referred to as old work boxes.
Old work boxes may include pressure/spring retaining latches. The latches are usually vertically and/or horizontally mounted to the exterior sides of the boxes and allow the box to be pushed through a wall opening. Once through the opening, the latches deploy by spreading beyond the rear edge of the wall opening. Pawls, commonly referred to as ears, wings, or fingers, are mounted on two or more opposing corners of the electrical work box. When deployed by means of a tightening screw, the pawls, in conjunction with opposing flanges integrally mounted on the front edges of the box, serve to clamp the box to the wall.
The retaining mechanisms employing latches and pawls often fail to securely mount the old work boxes in place. Where wall thickness varies, a thicker than typical wall may preclude pressure/spring retaining latches from expanding. A thinner than normal wall may result in space between the retaining latch and the rear wall surface and allow the box to move back and forth within the wall. Irregularities in the posterior wall surface in lathe and plaster walls or in insulating materials may also prevent pressure/spring retaining latches and/or screw activated pawls from properly deploying.
Further, in mounting electrical boxes using screw activated pawls, deployment of the pawls may over tighten the screw, resulting in stripping the threads in the pawl. As a result, the box must be dismounted and discarded and installation must be started over with a new box.
In view of the above difficulties, there is a need for a more reliable, quicker to use, and more versatile fastening system for electrical work boxes.